Directly controlling the distribution of digital artifacts is nearly impossible.
But such a definition of DRM is pointless and tries to brush over the fact that actual DRM implementations (as in copy-protection schemes used by Amazon, iTunes, Bluray, etc.) are worthless.
DRM is more like leaving your file on the desk and putting a lock on the Xerox machine.
DRM tries to keep people from making off with the stuff in the house after you've already let them in through the door.
DRM schemes seem mostly to be misunderstandings about how encryption and authentication fit together.
> Locks keep people out period.
Someone might be inside the house when they break in and that person might be armed.
Someone might see them opening the door with a crowbar and either report them or stop them.
They may be recorded on CCTV en-route to my house , or stopped the police and have to explain why they were carrying a crowbar late at night.
Even if they are not caught in the act, the incident will almost certainly be reported to the police afterwards.
None of these risks really exist in terms of breaking DRM.
If someone could break your house lock simply by tapping a button on their smartphone then I would suggest that locking your house is pointless.
Gosh, people who buy locks must be stupid, because anybody with a crowbar can simply pry the door out of its frame.
DRM deters people from copying content willy-nilly. You might argue about the quantitative results, but it does something, and as long as it has more value than it costs, people will pay for DRM.